Miasma Worm Hits 73 Microsoft GitHub Repositories in Major Supply Chain Attack

Microsoft’s GitHub repositories have become the latest to fall victim to the ongoing Miasma self-replicating supply chain attack campaign.

The incident impacted 73 Microsoft repositories across four of its GitHub organizations, including Azure, Azure-Samples, Microsoft, and MicrosoftDocs, per OpenSourceMalware. The development has GitHub to disable access to those repositories.

“Access to this repository has been disabled by GitHub Staff due to a violation of GitHub’s terms of service,” reads the message when attempting to access the “Azure/azure-functions-host” repository. “If you are the owner of the repository, you may reach out to GitHub Support for more information.”

According to OpenSourceMalware, the incident impacts the following repositories –

• azure-search-openai-demo-purviewdatasecurity
• Connectors-NET-LSP
• Connectors-NET-SDK
• durabletask
• durabletask-dotnet
• durabletask-go
• durabletask-js
• durabletask-mssql
• functions-container-action
• homebrew-functions
• llm-fine-tuning
• windows-driver-docs

What’s notable about the latest campaign is the re-compromise of the “durabletask” PyPI package, which was infected by TeamPCP last month to deliver an information stealer on Linux systems.

“A month later, not only is Azure/durabletask gone – so is every sibling repo in the Durable Task ecosystem, sitting one org over in Microsoft: the .NET, Go, Java, JS, MSSQL, Netherite, and protobuf implementations, plus the Durable Functions monitor,” security researcher Paul McCarty (aka 6mile) said.

“When the repo at the root of last month’s compromise is the hub of this month’s takedown, that is not a coincidence – that is the same wound reopening. Whoever held those credentials in May plausibly never fully lost them.”

Miasma is assessed to be a variant of the Mini Shai-Hulud worm that TeamPCP publicly released in mid-May 2026. It has since continued to mutate and refine its tactics, even as it has infected more packages over the past couple of days, using various descriptions of the public repositories containing the stolen secrets –

• Miasma: The Spreading Blight
• Miasma : The Spreading Blight
• Miasma – The Spreading Blight
• Hades – The End for the Damned

As of writing, there are 13 repositories with the description “Hades – The End for the Damned” and 82 repositories with the remaining three naming patterns.

Miasma has also been observed skipping the npm registry entirely, with the threat actors pushing malicious code directly to “icflorescu/mantine-datatable” and four related repositories: “mantine-contextmenu,” “next-server-actions-parallel,” “mantine-datatable-v6,” and “mantine-contextmenu-v6.”

“The commit added no dependencies. It planted a 4.3 MB payload runner and wired it to execute automatically through five developer tools: Claude Code, Gemini CLI, Cursor, VS Code, and the npm test script,” SafeDep said. “The attack detonates when a developer clones one of the affected repos and opens it in an AI coding agent. The dropper is the same staged Bun loader, here repurposed for GitHub source-repo persistence rather than registry poisoning.”